Forged from the toughest steel all Sunex Tools impact sockets are forged from the finest chrome molybdenum alloy stool- the best choice for strength and durability.Designed to extend the life of fasteners. All Sunex Tools impact sockets feature a radius corner design. This design causes the socket to grab the sturdy wall, or flat, of the fastener instead of grabbing the corners, resulting in less corner wear on the fastener.